Muscle Types Flashcards
Muscle types
Skeletal, cardiac and visceral (smooth)
Muscle functions
- each muscle type undergoes the process of shortening or contraction
- contraction process causes movement of body parts and organs
Skeletal muscle
Location
Each end is attached to a different bone at its origin and insertion
Skeletal muscle
Function
- moves the bones or a body part during the contraction process
- since contraction is controlled by conscious thought, the muscle action is said to be voluntary
Skeletal muscle
Tissue structure
Components
-composed of bundles of cells surrounded by connective tissue
Skeletal muscle
Tissue structure
Tissue arrangement
-fascicles, endomysium, perimysium, epimysium, tendon, aponeurosis
Fascicles
Band or bundle of nerve or muscle fibers
Endomysium
(Deep layer) surrounds muscle fibers
Perimysium
(Middle layer) surrounds fasciculi
Epimysium
(Superficial layer) surrounds groups of fasciculi; surrounds muscle
Tendon
(Band or chord) extensions of fibrous tissue beyond muscle cells
-forms string structure to anchor muscle to bone or other muscle
Aponeurosis
Wide ban of fibrous tissue between some muscles
Ie. scalp and abdomen
Skeletal muscle
Cell structure
- fibers (cells): very long and cylindrical; extends the length of muscle fasiculi, which in some cases is the length of the muscle
- nuclei: multiple; peripherally located
- striations: yes
Cardiac muscle
Location
- found in the walls of the heart
- composes most of the structure of the heart
Cardiac muscle
Function
- main action is to move blood through blood vessels as it contracts
- -this ensures delivery of blood to all body cells and tissues
- process of contraction is involuntary
- -heart contraction is controlled by the pacemaker tissue and by the autonomic nervous system
Cardiac muscle
Tissue structure
- cells are branched and connect to each other by intercalated disks
- little connective tissue between the cells
- cells form large units that can contract together
Myocardium
Muscle of the heart
Cardiac muscle
Cell structure
- fibers: cylindrical and branched
- nucleus: single; centrally located
- striations: yes
- intercalated disks: joins cells to one another
Visceral (smooth) muscle
Location
Located in the walls of most internal organs
Visceral (smooth) muscle
Functions
- contraction controls the actions of the internal organs such as the stomach, intestines, respiratory tubes and reproductive organs
- substances are moved through these organs as the muscle in the wall contracts
- involuntary and controlled by autonomic nervous system and hormones
Visceral (smooth) muscle
Tissue structure
- arranged in large sheets with many gap junctions between cells (unitary smooth muscle: contracts as a whole unit)
- fewer gap junctions and cells (or groups of cells) tend to act as independent units (multi unit smooth muscle)
Visceral (smooth) muscle
Cell structure
- fibers: spindle shaped
- nucleus: single; centrally located
- smooth appearance, no striations
Rectus abdominus
Origin: pubic crest, symphysis pubis
Insertion: inferior ribs, xiphoid process
Action: flexes vertebral column
External oblique
Internal oblique
Transverse abdominus
Compress abdomen and rotate trunk
